In conventional absorbent articles, an absorbent body is provided between a liquid impermeable backsheet, such as a polyethylene sheet or a non-woven fabric made of laminated polyethylene sheets, and a liquid permeable topsheet, such as a non-woven fabric or a permeable plastic sheet.
This kind of absorbent article has been improved many times, and a variety of absorbent articles, in particular, such as a light incontinence pad, has been proposed that have a concave groove formed in its top surface along a longitudinal direction thereof and functions as a urine temporary storage and distributing unit for receiving urine surging out at one time in a small area and rapidly distributing the received urine.
For example, Patent Document 1 describes an absorbent article that includes an upper absorbent layer provided on a skin-contacting side and a lower absorbent layer provided on a non-skin-contacting side. The upper absorbent layer and the lower absorbent layer form a middle high portion that has a groove formed in the skin contacting side and extending in the longitudinal direction of the absorbent article. The groove is an opening portion penetrating through the upper absorbent layer, and the lower absorbent layer is located under the lower surface of the upper absorbent layer so as to form a bottom surface of the opening portion.
Moreover, Patent Document 2 describes an absorbent article that includes an absorbent layer including a lower absorbent layer and an upper absorbent layer, stacked on the lower absorbent layer, that have different areas from each other so as to form a step portion having a difference in level. A concave portion is formed in a topsheet and the absorbent layer together so as to extend in a longitudinal direction of the absorbent article. The concave portion is continuously formed throughout the upper portion and the lower portion including the step portion while passing the center of the absorbent layer in a width direction of the absorbent article without being interrupted by the step portion of the absorbent layer.
Furthermore, Patent Document 3 discloses an absorbent article that has an embossed groove whose bottom surface has highly compressed portions extending from an inner edge toward an outer edge but not reaching the outer edge and intermittently arranged in a longitudinal direction of the groove, and highly compressed portions extending from the outer edge toward the inner edge but not reaching the inner edge and intermittently arranged in the longitudinal direction of the groove so that the highly compressed portions formed from the inner edge and the highly compressed portions formed from the outer edge are alternately arranged in the longitudinal direction of the groove, in order to prevent the embossed groove portion from hardening and a body fluid in the embossed groove from spreading.